The present invention relates to a multi-point connection module for a transformer coil, and to a transformer comprising such a multi-point connection module.
Power or distribution transformers are electrical devices used to transfer energy from one circuit to another. They utilize the principle of electromagnetic induction to step up or down a certain voltage level to a higher or lower voltage level. As it is known, electromagnetic induction induces a voltage on a conductor which is placed in a varying magnetic field. In transformers, the varying magnetic field is produced by applying an alternating current to a transformer coil, generally indicated as a primary coil or winding. This primary winding is normally coupled to a secondary winding or coil, and both primary and secondary windings, which comprise each a plurality of turns, are wound around a magnetic core. When the alternating current is applied to the primary winding, a varying magnetic flux is induced in the core and a voltage in the secondary coil is produced.
Besides unavoidable losses which are always present, the ratio of the voltages across the primary winding and the secondary winding is ideally equal to the ratio between the number of turns in the primary winding and in the secondary winding. Thus, by changing the ratio between the number of turns of the primary and the secondary windings, the ratio of the voltages can be changed. In this way, it is possible to control or regulate the voltage across the secondary winding which represents the output voltage supplied by the transformer, for example to any load connected therewith.
To this end, transformers are provided with specific connections which are referred to as taps in the transformer industry. The transformer taps are electrical connection points which are positioned along either the primary and/or the secondary windings and allow the number of turns to be selected. The selection of the tap to be used is made via a tap changer mechanism. For instance, the tap changer mechanism selects which turn in the secondary coil will be connected to a load circuit thereby varying the ratio of turns in the transformer and regulating the output voltage.
At present, for each coil there is provided a certain number of single connection taps, e.g. which are each attached to a corresponding turn in the coil and then are all brought out to the face of the coil. Usually, each tap is constituted by either a lug or a flat bar and in most cases the taps are welded inside the coil. Then, the taps are connected typically by a cable on the face of each coil.
This use of single connection taps as described above has some shortcomings, in particular as regard to the time required in the coil winding manufacturing process, to the content of material used, and also to the transformer enclosure depth size.
It would therefore be desirable to provide a solution which allows to optimize the manufacturing time in the coil winding process, to minimize the space needed inside the transformer enclosure, and to reduce the material costs associated with the transformers.